We will search for the mechanism of action of the hormone, insulin, using isolated liver and adipose cells and enzymes extracted from such cells. We will search for the defect in protein synthesis that is characteristic of diabetes. The "third mode" of action of insulin, inhibition of cyclic AMP-dependent protein kinase, will be studied to determine the mechanism by which insulin decreases the affinity of the kinase site 2 for cyclic nucleotides. The role of insulin in a new mechanism of regulating glycogen synthesis will be examined using isolated hepatocytes from diabetic rats to determine whether they can respond to the combination of glutamine, leucine, and dehydroxyacetone. This combination stimulates the conversion of glycogen synthase b to a in cells and will now be studied in cell-free enzyme preparations.